On Aug. 18, David Miranda, the Brazilian partner of American journalist Glenn Greenwald, was stopped and held at Heathrow for nine hours, the legal maximum under the country’s antiterrorism law, before being released without charge. Though not a journalist, Miranda was on his way back to the home he shares with Greenwald, in Brazil, from Germany where he had been doing work for his partner. Greenwald is the Guardian journalist who broke the story of secret state surveillance programs in the U.S. based on information leaked by former NSA employee Edward Snowden. Miranda has stated that he had been in Berlin meeting with American filmmaker Laura Poitras, who has also been working with Greenwald on Snowden’s files.

According to Miranda, all of his electronic equipment had been confiscated by British police. “I stayed in a room, there were six different agents, entering and leaving, who spoke with me,” he told the Associated Press in Rio de Janeiro after returning from Heathrow. “They asked questions about my whole life, about everything. They took my computer, video game, cell phone, memory thumb drives, everything.”

The incident prompted a critical response from the Guardian’s editor in chief Alan Rusbridger — and brought out a new revelation. In an article posted on Aug. 19, Rusbridger described how the British government had recently attempted to persuade him to destroy the documents leaked by Snowden. When Rusbridger resisted, he says he was threatened with legal action before officials from the Government Communications Headquarters (GCHQ) were sent to the Guardian’s London offices to destroy computers containing the documents themselves.

And so one of the more bizarre moments in the Guardian’s long history occurred — with two GCHQ security experts overseeing the destruction of hard drives in the Guardian’s basement just to make sure there was nothing in the mangled bits of metal which could possibly be of any interest to passing Chinese agents.

While the British government has not yet responded to Rusbridger’s claim, many media commentators in both the U.K. and the U.S. are disturbed by the revelation. Paul Staines, a right-leaning British political commentator, wrote on his website on Aug. 20, “What this comes down to is that state security was in the Guardian’s basement destroying their hard drives. Which is a hugely worrying development.” Across the pond, Ryan Chittum at the Columbia Journalism Review wrote, “In light of Rusbridger’s disclosures, it’s even clearer that the detention of Miranda is part of an attack on American journalists authorized at the highest levels of the British government.”

Regarding Miranda’s ordeal at Heathrow, the British authorities have since stated that they were within their rights to detain Miranda under Schedule 7 of Britain’s Terrorism Act 2000, which allows authorities to detain and question people traveling through ports and airports to determine whether they are involved in planning terrorist attacks. The U.K. Home Office released a statement saying, “The government and the police have a duty to protect the public and our national security. If the police believe that an individual is in possession of highly sensitive stolen information that would help terrorism, then they should act and the law provides them with a framework to do that. Those who oppose this sort of action need to think about what they are condoning.”

Spokespeople for both the White House and Downing Street have said while they were made aware of Miranda’s detainment, neither was involved in the decision to do so.

Rusbridger says the Guardian, which has recently expanded its American operations, intends to pursue the Snowden story, however “we just won’t do it in London.” Miranda has stated he intends to legally challenge the U.K. Home Office over its confiscation of his electronics and Rusbridger has pledged the Guardian’s support.